Low grade fuel is a cheap fuel and it would be desirable to use it to fuel gas turbines. However, low grade fuel contains undesirable contaminants, such as organic vanadium and nickel compounds, which have detrimental corrosion effects on gas turbines. Accordingly, it is necessary to remove the contaminants from the low grade fuel before it can be used in gas turbines.
Vanadium present in fuel is in a soluble porphyrin form and is difficult to remove by conventional separation techniques. Fractional distillation, for example, is capital intensive and requires highly skilled labor to operate. It is not suitable for frequent start-up and shut-down operations, and the footprint for distillation columns can also be very large. Adsorption of vanadium and nickel porphyrins on a solid sorbent can be used. However, conventional adsorption columns may not be readily applied to the removal of vanadium from very viscous fuels, as the pressure drop in such columns is very high.
U.S. Publication No. 2006/0011511 A1 published on Jan. 19, 2006, discloses a heavy oil reforming method for preparing fuel suitable for a gas turbine. The heavy oil is reacted with supercritical water and then with a scavenger to eliminate sulfur and vanadium from the heavy oil.
What is needed is an improved method for removing metals from low grade fuel.